1. Field of the Invention
The present invention relates to an information retrieval system in which any information item stored in plural information servers is retrieved via a host server. This application is based on Patent Application No. Hei 9-206956 filed in Japan, the contents of which are incorporated herein by reference.
2. Description of the Related Art
Regarding conventional vehicle navigation systems respectively mounted to plural vehicles, the following method is known such that positional information of a relevant vehicle is sent to another vehicle having a similar system, and positional information of another vehicle is also received by the relevant vehicle and the indicated position of the other vehicle is shown on a map, where the relevant vehicle is shown at the center of the map.
In recent vehicle navigation systems such as the VICS (Vehicle information and Communication System), the following method is known such that traffic information (relating to a closed area or a traffic jam caused by construction, an accident, etc.) sent from an information center, which is originally provided by a specific organization or the like, is received and displayed on a monitor screen, and a new route for avoiding the traffic jam or the like is presented based on the received traffic information.
On the other hand, information communication via the Internet is widely spread nowadays, and various information items can easily be obtained from world-wide computers connected to the Internet. Usually, in information servers (homepages, or the like) connected with the Internet, detailed information items (i.e., contents) are stored in correspondence to a URL (Uniform Resource Locator) of the server in the network.
Regarding the above-mentioned navigation systems, the former can acquire only positional information of other vehicles, while the latter can acquire only traffic information provided by an information center. That is, the amount of possibly acquired information is restricted. In contrast, in information communication via the Internet, a great amount of information can be acquired. However, in this case, connection from a personal computer, a work-station, or the like is necessary on the premise and direct access to the Internet from the existing navigation system has been impossible.
In addition, an extremely great number of computers are connected to the Internet, and it is difficult to judge the content of each information item stored in a server with only reference to the title of a corresponding home page or a relevant URL. Therefore, it is difficult to specify a server which stores information desired by a user.
In consideration of the above circumstances, an object of the present invention is to provide an information retrieval system by which necessary information can be easily and accurately obtained from among a great amount of information items by using a communication terminal which is mounted on a movable object or is fixedly disposed.
A particular object of the present invention relates to an information retrieval system for acquiring information on a possible destination or various establishments, in which information to be acquired can be specified according to a position corresponding to the information and the present position of a relevant communication terminal.
In order to realize the above objectives, the present invention provides an information retrieval system comprising a communication terminal for retrieving, via a host server, information stored in plural information servers connected to a network, wherein:
the host server stores summary information relating to information items stored in the information servers, addresses of these information servers in the network, and positional information on each information item stored in each information server;
each of the information servers stores relevant information items, summary information, and an address in the network;
the communication terminal accesses the host server and sends present positional information of the communication terminal to the host server;
the communication terminal makes the host server send the communication terminal summary information relating to the information items stored in the information servers and the corresponding addresses in the network, specified according to the positional information on each information item stored in each information server and to the present positional information of the communication terminal;
the communication terminal identifies at least one of the information servers which stores a desired information item according to the received summary information on the information items stored in the information servers; and
the communication terminal accesses the identified information server with reference to the received address of the relevant information server in the network.
The positional information on each information item stored in each information server relates to the physical position of an object (like a facility) indicated by the information item stored in a relevant information server. In conventional information servers, such positional information relating to the stored information item is not stored. According to the present invention, it is possible to specify a desired information server (which stores desired information with respect to any place, facility, or the like) with reference to positional relationships between the above physical position (relating to the desired server) and the present positional information of the communication terminal, and to access the desired information server using the address (URL) of the information server.
The present invention can preferably be applied to a navigation system. In this case, the communication terminal is a navigation device mounted to a vehicle; and the navigation device detects the present position of the vehicle and sends information of the present position to the host server, and receives information stored in any information server based on the present position of the vehicle and the address of the information server in the network. If information relating to a destination of a drive is necessary, it is possible to more accurately specify retrieved information suitable for an object of the drive.
Accordingly, necessary information can be easily and accurately obtained from among a large number of information items by using a communication terminal which is mounted on a movable object or is fixedly disposed.
The following structure is also possible in which the host server further stores category data relating to the information items stored in the information servers; and the communication terminal makes the host server send these category data to the communication terminal, sends a desired information category to the host server, and makes the host server send the communication terminal summary information of each information item stored in the relevant information server, specified according to the sent desired information category, and the address of the relevant information server in the network.
In this case, the desired information may more easily be specified according not only to the positional relationship but also to additional summary information on the information servers like category data.
The present invention also provides an information retrieval method in which a communication terminal retrieves, via a host server, information stored in plural information servers connected to a network, wherein:
the host server stores summary information relating to information items stored in the information servers, addresses of these information servers in the network, and positional information on each information item stored in each information server; and
each of the information servers stores relevant information items, summary information, and an address in the network, and
the communication terminal performs the steps of:
accessing the host server and sending present positional information of the communication terminal to the host server;
making the host server send the communication terminal summary information relating to the information items stored in the information servers and the corresponding addresses in the network, specified according to the positional information on each information item stored in each information server and to the present positional information of the communication terminal;
identifying at least one of the information servers which stores a desired information item according to the received summary information on the information items stored in the information servers; and
accessing the identified information server with reference to the received address of the relevant information server in the network.
The present invention further provides a computer readable storage medium for a communication terminal, which stores an information retrieval program for performing the above steps in the above method.